Meta

Purpose Evidence on the association between coffee consumption and prostate cancer

Purpose Evidence on the association between coffee consumption and prostate cancer risk is inconsistent; furthermore, few studies have examined the relationship between coffee consumption and fatal prostate cancer. six or more cups per day to nondrinker were; 0.94 (0.86C1.02), p-trend=0.08 for overall prostate cancer, 1.13 (0.91C1.40), p-trend=0.62 for advanced prostate cancer and 0.79 (0.53C1.17), p-trend=0.20 for fatal prostate cancer. The findings remained nonsignificant when we stratified by prostate specific antigen (PSA) testing history or restricted to nonsmokers. Conclusions We found no statistically significant association between coffee consumption and the risk of overall, advanced or fatal prostate cancer in this cohort, though a modest reduction in risk could not be excluded. Keywords: Coffee, caffeine, prostatic neoplasms, prospective studies Introduction Coffee contains multiple chemical compounds that are known to have biological activity and some of these compounds may have potentially beneficial effects (1). Long-term coffee intake has been consistently associated with lower risk of type 2 diabetes, better glucose metabolism and lower insulin levels (2, 3). Coffee could affect the risk of prostate cancer through the antioxidant and anti-inflammatory effects of its beneficial components including lignans, phytoestrogens and chlorogenic acids (4C6). Coffee has also been associated with lower levels of IGF-1 and circulating sex hormones which are associated with prostate cancer progression (7, 8). Epidemiological evidence of the relationship between coffee consumption and prostate cancer is inconsistent. Several prospective studies found no significant association between coffee intake and risk of prostate cancer (9C12). However, many of these adjusted for only a few confounding factors and lacked information on disease stage and grade. Adjustment for smoking is particularly important since smoking is linked Rabbit Polyclonal to HSF2 with increased coffee intake in many populations, and is independently associated with higher risk of prostate cancer mortality (13, 14). A meta-analysis of five cohort studies reported an inverse association between coffee consumption and overall prostate cancer risk, with a summary estimate of 0.76 (95% confidence interval (CI) 0.61, 0.98) for highest drinkers vs. non/low drinkers (15). A recent study reported a marked decrease in risk of lethal (but not overall) prostate cancer (8). The aim of our analysis was to examine the association between coffee consumption and risk of fatal, advanced and overall prostate cancer in a large cohort with long follow up and information on multiple potential confounders. Methods Study population The NIH-AARP Diet and Health Study was initiated in 1995C1996, when AARP members aged 50 to 71 years old residing in six U.S. states (California, Florida, Louisiana, New Jersey, North Carolina, and Pennsylvania) and two metropolitan areas (Atlanta and Detroit) responded to a questionnaire eliciting information on dietary behaviors, demographic characteristics and other health-related information (n=566,398) (16). Completion of the self-administered questionnaire was considered to imply informed consent to participate in the study. In a subsequent mailed questionnaire (1996C1997, 69% response rate) participants reported their history of prostate specific antigen (PSA) testing and digital rectal examinations during the previous three years. For our analyses, we excluded 14,495 men whose questionnaires were completed by others, as well as 27,270 with cancer other than nonmelanoma skin cancer at baseline, 626 with self-reported kidney failure, 2,575 who reported extreme Bosentan intake of total energy (exceeding twice the interquartile ranges of log-transformed intake), 1,273 with missing coffee intake information, and 5,036 who died in the first 2 years of follow-up, leaving an analysis dataset of 288,391 men. The NIH-AARP Diet and Health Study was approved by the Special Studies Institutional Review Board of the National Cancer Institute. Assessment of exposure At baseline, participants completed a 124-item food frequency questionnaire that assessed dietary intake over the previous 12 months, including caffeine containing drinks such as coffee, tea and soft drinks (17). Consumption was assessed in frequency categories ranging from 0 to 6 or more cups per day and almost 90% of coffee drinkers provided information on whether they drank caffeinated or decaffeinated Bosentan coffee more than half the time. The questionnaire Bosentan also included foods that contain small amounts of caffeine. Total daily caffeine intake was calculated based on the food items, portion sizes and nutrient database constructed using the US Department of Agricultures 1994C1996 Continuous Survey of Food Intake by Individuals (18). The FFQ was.